1. Field of the Invention
The present invention relates to the art used for a battery system, particularly a battery system for vehicle, an on-vehicle battery module, a cell controller, etc.
2. Description of Related Art
There is a battery system, particularly a battery system for vehicle drive, using a lithium ion battery known in the related art that diagnoses over-charge and over-discharge of the battery cells (Patent Literature 1: Japanese Laid Open Patent Publication No. 2005-318751). The battery system includes a function for diagnosing the operating condition of the cell voltage balancing circuit provided for narrowing differences in state of charge among the battery cells. Furthermore, the art for sensing a disconnection of the wire harness between the battery cell and the circuit which is to detect terminal voltages is also known (Patent Literature 2: Japanese Laid Open Patent Publication No. 2006-294339).
The battery system for vehicle drive is required to monitor the state of the battery cell via adjustment of state of charge by the cell voltage balancing circuit or via over-charge and over-discharge diagnosis. Furthermore, overall reliability of the battery system should be improved not only through monitoring the state of the battery cell but also through improving reliability of the measurement system. An object of the present invention is to provide a battery system for vehicle assuring a high level of safety.